Liquid crystal display comprising a touch panel and a bandpass filter

ABSTRACT

A liquid crystal display includes a first flat glass substrate, an opposite second flat glass substrate, a liquid crystal layer sandwiched therebetween, a backlight module disposed adjacent to the first flat glass substrate, a color filter disposed adjacent to the second flat glass substrate, a bandpass filter member disposed on the color filter. The bandpass filter member is configured for allowing light of a given spectrum emitted from the backlight module to pass therethrough and blocking light that is not in the given spectrum from passing therethrough, and a touch panel disposed adjacent to the bandpass filter member.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to, and claims the benefit of, a foreignpriority application filed in China as Application No. 200810302286.3 onJun. 24, 2008. The related application is incorporated herein byreference.

BACKGROUND

1. Technical Field

The present disclosure generally relates to a liquid crystal display,and particularly relates to a liquid crystal display having a mirrorfunction.

2. Discussion of Related Art

Nowadays, liquid crystal displays (LCD) are extensively employed invarious electronic devices, such as mobile phone, television, etc. Atypical LCD usually does not have the full capabilities as a mirror(e.g. to be used for applying make up). People have to take along acosmetic mirror with them to meet a demand of making up at any moment ordispose a mirror for dressing at home. It is not convenient andspace-occupied. Therefore, it is necessary to develop a liquid crystaldisplay capable of being used as a mirror.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the different views.

FIG. 1 is a cross-section view of a liquid crystal display including abandpass filter member in accordance with a first embodiment.

FIG. 2 shows a transmittance spectrum of the bandpass filter member.

FIG. 3 is a cross-section view of a liquid crystal display in accordancewith a second embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring to FIG. 1, a liquid crystal display (LCD) 100 provided in afirst embodiment includes a backlight module 10, a first flat glasssubstrate 20, a second flat glass substrate 40, a liquid crystal layer30, a color filter 50, a bandpass filter member 60 and a touch panel 70,which are sequentially arranged in the order written, along atransmission direction of the light emitted from the backlight module10.

The backlight module 10 is a typical liquid emitting diode lightresource, including a light emitting surface 11, configured for emittingwhite light beams comprised of red, green and blue light beams, to theliquid crystal layer 30 through the first flat glass substrate 20. Thefirst flat glass substrate 20 contacts the emitting surface 11 of thebacklight module 10. The second flat glass substrate 40 is opposite tothe first flat glass substrate 20. The liquid crystal layer 30 issandwiched between the first and second flat glass substrates 20, 40,including a plurality of liquid crystal molecular (not shown) and twoopposite transparent electrodes (not shown). The liquid crystal issandwiched between the two electrodes. The color filter 50 is disposedon a surface of the second flat glass substrate 40, and is configuredfor converting white light beams transmitted therethrough into red lightbeams, green light beams and blue light beams. The red, the green andthe blue light beams are used to irradiate the touch panel 70 therebydisplaying color images.

The bandpass filter member 60 is disposed on a surface of the colorfilter 50. The bandpass filter member 60 includes a transparent plate 61and a bandpass filter film 62 formed thereon. The bandpass filter film62 faces the touch panel 70, and includes a number of (e.g., 15 to 22)alternately arranged first and second layers (not shown). The bandpassfilter film 62 is configured for allowing light of a given spectrumemitted from the backlight module 10 to pass therethrough, and blockinglight that is not in the given spectrum from passing therethrough. Thus,all the light beams emitted from the backlight module 10 and thenpassing through the color filter 50 can pass through the bandpass filter62. The first layers are comprised of a first material and the secondlayers are comprised of a second material. A refractive index of thefirst material is in a range from 2.1 to 2.5; and a refractive index ofthe second material is in a range from 1.3 to 1.5. The first material isselected from a group consisting of Ta₂O₅, TiO₂, Ti₃O₅, and Nb₂O₅. Thesecond material can be SiO₂. In addition, the transparent plate 61 canbe omitted. Under this situation, the bandpass filter film 62 isdirectly formed on the surface of the color filter 50.

The touch panel 70 is configured for sensing operation of a user anddisplaying images according to instructions of a controller (i.e., a CPUof an electronic device) and displaying color images. As such, the touchpanel 70 is capable of displaying handwriting of a user. Therefore, theliquid display 100 achieves a function of an electronicnotebook/blackboard.

In the embodiment, when the backlight module 10 emits white light beams,the bandpass filter member 60 entirely transmits the white light beamsto the touch panel 70, and the touch panel 70 displays color images.When the backlight module 10 does not emit light beams, an entiresurface of the touch panel 70 reflects the external light beamsirradiated thereon except for the red, green and blue light includedtherein; and the liquid crystal display 100 achieves a mirror function.

Referring to FIG. 3, another liquid crystal display 200 of a secondembodiment is provided, differing from the previous embodiment infurther inclusion of a transreflective layer 280 including a number ofreflecting regions 281 and transmitting regions 282. The reflectingregions 281 and the transmitting regions 282 are alternately arranged.The reflecting regions 281 reflect light beams irradiated thereon suchthat the LCD 200 can display image even without a backlight module. Thetransmitting region 282 is capable of transmitting the light beamsemitted from the backlight module 210 such that the LCD 200 can displaya high brightness image under the irradiating of the backlight beams.Preferably, each reflecting region 281 includes a plurality ofnanoparticles disposed on a reflecting surface (not shown) thereof toimprove a reflective index thereof. Furthermore, the color filter 250 issandwiched between the first flat glass substrate 220 and the reflectinglayer. The bandpass filter member 260 is disposed between the secondflat glass substrate 240 and the touch panel 270.

While certain embodiments have been described and exemplified above,various other embodiments will be apparent to those skilled in the artfrom the foregoing disclosure. The present invention is not limited tothe particular embodiments described and exemplified but is capable ofconsiderable variation and modification without departure from the scopeof the appended claims.

1. A liquid crystal display, comprising: a first flat glass substrate,an opposite second flat glass substrate, and a liquid crystal layersandwiched therebetween; a backlight module disposed adjacent to thefirst flat glass substrate; a color filter disposed adjacent to thesecond flat glass substrate; a bandpass filter member disposed on thecolor filter, the bandpass filter member being configured for allowinglight of a given spectrum emitted from the backlight module to passtherethrough, and blocking light emitted from the backlight module thatis not in the given spectrum from passing therethrough; and a touchpanel disposed adjacent to the bandpass filter member; wherein thebandpass filter member is further configured for allowing light of thegiven spectrum emitted from outside of the liquid crystal display topass therethrough, and reflecting light emitted from outside of theliquid crystal display that is not in the given spectrum, such that whenthe backlight module is turned off, the light from outside of the liquidcrystal display passes through the touch panel and reaches the bandpassfilter member, and the bandpass filter member reflects the light that isnot in the given spectrum so as to make the liquid crystal displayachieve a mirror function.
 2. The liquid crystal display as claimed inclaim 1, wherein the bandpass filter member comprises a bandpass filterfilm including a number of alternately arranged first and second layers,and the bandpass filter film is proximate to the touch panel.
 3. Theliquid crystal display as claimed in claim 2, wherein the first layersare comprised of a first material, a refractive index of the firstmaterial is ranged from 2.1 to 2.5, the second layers are comprised of asecond material, and a refractive index of the second material is rangedfrom 1.3 to 1.5.
 4. The liquid crystal display as claimed in claim 3,wherein the first material is selected from a group consisting of Ta₂O₅,TiO₂, Ti₃O₅, and Nb₂O₅, and the second material is SiO₂.
 5. The liquidcrystal display as claimed in claim 1, wherein the bandpass filtermember comprises a transparent substrate and a bandpass filter filmformed on a surface of the transparent substrate, and the bandpassfilter film is adjacent to the touch panel and includes a number ofalternately arranged first and second layers.
 6. The liquid crystaldisplay as claimed in claim 5, wherein the first layers are comprised ofa first material, a refractive index of the first material is rangedfrom 2.1 to 2.5, the second layers are comprised of a second material,and a refractive index of the second material is ranged from 1.3 to 1.5.7. The liquid crystal display as claimed in claim 6, wherein the firstmaterial is selected from a group consisting of Ta₂O₅, TiO₂, Ti₃O₅, andNb₂O₅, and the second material is SiO₂.
 8. The liquid crystal display asclaimed in claim 1, further comprising a transflective layer disposedbetween the first flat glass substrate and the backlight module, thetransflective layer including a number of alternately arrangedreflecting regions and transmitting regions.
 9. A liquid crystaldisplay, comprising: a first flat glass substrate, an opposite secondflat glass substrate, and a liquid crystal layer sandwichedtherebetween; a backlight module disposed adjacent to the first flatglass substrate; a color filter disposed adjacent to the second flatglass substrate; a bandpass filter member disposed on the color filter,the bandpass filter member being configured for allowing light of agiven spectrum emitted from the backlight module to pass therethrough,and blocking light emitted from the backlight module that is not in thegiven spectrum from passing therethrough; and a touch panel disposedadjacent to the bandpass filter member; wherein the bandpass filtermember is capable of reflecting external light that is not in the givenspectrum, and allowing external light that is in the given spectrum topass therethrough, such that when no light is emitted from the backlightmodule, the external light passes through the touch panel and reachesthe bandpass filter member, and the bandpass filter member reflects theexternal light that is not in the given spectrum, so that the liquidcrystal display achieves a mirror function.
 10. The liquid crystaldisplay of claim 9, wherein the bandpass filter member comprises abandpass filter film formed by a number of alternately arranged firstand second layers, and the bandpass filter film is directly formed on asurface of the color filter that is away from the liquid crystal layer.11. The liquid crystal display of claim 10, wherein the first layers arecomprised of a first material, a refractive index of the first materialis ranged from 2.1 to 2.5, the second layers are comprised of a secondmaterial, and a refractive index of the second material is ranged from1.3 to 1.5.
 12. The liquid crystal display of claim 9, wherein thebandpass filter member comprises a bandpass filter film and atransparent plate, the transparent plate is formed on a surface of thecolor filter that is away from the liquid crystal layer, and thebandpass filter film is formed on the transparent plate.
 13. The liquidcrystal display of claim 12, wherein the first layers are comprised of afirst material, a refractive index of the first material is ranged from2.1 to 2.5, the second layers are comprised of a second material, and arefractive index of the second material is ranged from 1.3 to 1.5.